Sand trap



Sept 27, 1932 RQ A. LiGH-r ET AL 1,879,810

SAND TRAP Filed March 24, 1932 Muff/wams Patented Sept. 27, 1932 UNITED STATES PA TENT OFFICE RALPH A. LIGHT, OF CYNWYD, AND JOSEPH W. PRICE, JR., OF PHILADELPHIA, PENN- SYLVANIA, ASSIGNORS TO THE UNITED STATES METALLIC PACKING COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA SAN D TRAP Application led Hatch 24, 1932. Serial No. 600,934.

Our invention relates to the construction and mode of operation of air distributor valves used in connection wit-h sander systems such as are used with locomotives, in which a sand trap is provided with two nozzles, one directed into the sand retaining rece tacle of the trap and operating when air is orced through it to blow a supply of sand out of the trap into the delivery pipe connected with it and leading to the rails. This nozzle we will refer to as a distributing nozzle, while the second nozzle is directed into the sand delivery pipe and operates when air is delivered to it to blow out any obstructions which may have been built up in the delivery pipe. This nozzle we will refer to as the blow-out nozzle. A trap of the kind described is illustrated in our former Patent 1,800,548, granted April 14, 1931.

In the operation of traps of the kind indicated it is important that air should be directed into and through the blow-out nozzle at the beginning of a sanding operation and should be, after a short interval, cut olf from this nozzle, leaving the distributing nozzle in operation. This can be accomplished in many ways and a number of automatic distributing valves have been devised, which when `air is admitted to the conduit leading to the sandl trap, operate to permit a short and energetic blast of air through the cleanout nozzle of the trap and then to cut'o this blast. The object of our invention is to provide an automatic distributing valve of a novel and highly efficient character in -4 which the turning on of pressure air to effect the sanding of the rails effects a reciprocatory movementof the distributing valve which controls the delivery of air to the clean-out nozzle so that this valve, which is normally closed, is first moved to open the port leading to the nozzle and then after a short interval, shifted in an opposite direction to again close the port.

The nature of our improvement will be best understood as described in connection with the drawing in whichit is illustrated in what we believe to be its most effective form and in which we have shown our improved distributingqvalve in asspciation wit'haV vsand trap having the features of our prior Patent 1,800,548, and our application for patent filed May 9, 1931, Serial No. 536,172.

Figure l of the drawing is a vertical sectional view through the distributing valve apparatus and 1through the associated sand trap, and

Figure 2 is a similar view on a reduced scale of a modification of the construction shown in Fig. 1.

Referring first to the construction illustrated in Fig. 1, the sand trap proper, which with the exception of its novel combination with the distributing valve constitutes no part of our present invention, consists of a sand receptacle A, connected to receive sand from a sand box through a conduit B. From the upper part of the sand receptacle a passage C leads to a delivery opening D, to which is connected the delivery pipe leading to the rail. E indicates a delivery nozzle directed into the sand receptacle A and so designed and proportioned as t0 deliver a limited amount of air suliicient to stir up the sand in the receptacle and carry a portion of it through the passage C to the delivery opening and pipe D. As shown, this nozzle E is connected with a chamber El formed in the casting and which chamber is also connected to a nozzle E2 directed into the delivery passage of the trap and located as shown in the center of the blowout. nozzle F, to be described. The chamber El has leading into it a restricted passage e connected with an expansion chamber e2 into which air passes through a passage e connected in turn with the air transmission chamber G2.

As shown, the effective air transmitting capacity of the passage e is made regulable by means of aneedle valve indicated at e1. The passage e3 receives air from the air supply conduit, as shown, through the air transmission chamber of the casing G, to be described. F indicates a blow-out nozzle directed into the delivery passage of the trap and designed to direct a high pressure jet of air of consion chamber. G is the casing of an improved air distributing valve, which, as shown, "1s preferably formed as an integral part of the body casting of the sand trap. This casing 1s divided into two chambers by a movable partition, preferably formed as a flexible dia.- phragm H, dividing it into an air retaining chamber G1 and an air transmitting chamber G2. This diaphragm as shown, is seated on an annular shoulder 3, formed in the casing G and clamped against this shoulder by an annular plug O, screwing into a threaded end ofthe casing G and having a closed outer end, as indicated at O1. To provide a connection between the restricted passage L and the chamber G1 in the construct-ion illustrated the edge of the plug O is grooved, as indicated at O2, in such manner that the groove will register with a perforation H2 formed through the edge of the diaphragm and this groove connects with the chamber G1 through one or more passages, as indicated at O3. I is an air admission port opening into the transmission chamber G2 and connected withl an air transmission pipe, indicated at I1, which leads to the ordinary engineers valve, not shown, employed for admitting and cutting off high pressure air. J is an outlet port from the transmission chamber G2, which is connected to the blow-out nozzle F. This port is preferably located, as shown, in a wall of the transmission chamber lying directly opposite to the movable partition or diaphragm H. e3 is a restricted passage leading through the wall of the transmission chamber G2 connected as shown and as heretofore described with the delivery nozzle E. is a restricted air passage, which, as shown,

is formed in the wall of the casing (Eh-'con-| necting the port I with the air retaining chamber G1. Any restricted connection which will place this air retaining chamber.V in, connection with the air supply-pipe'gwould` serve the same purpose. M indicates avalvefv adapted to open and close the port J The valve is shown as having a flat facefand is -formed on the end of a spindle extension-H1, secured to the center of the diaphragm H..

' that when pressure air is cut oil from the distributing valve the spring N pressing against the movable partition, as shown, the diaphragm H, will move it and its attached valve in the direction to close the port J. When pressure air is turned into the conduit I1 it will enter the transmission chamber G2 through the port I and will exert pressure on the diaphragm H, moving it toward the chamber G1 and opening the valve M so thatl lthe pressure air will pass freely through thev port J to the blow-out nozzle F. In the construction illustrated the airwill pass through the restricted passage e2 and its connected conduit passages to the distributing nozzle F` and to the nozzle E2 but this distributing nozzle and its connected passages arein practice so formed and arranged that the amount and pressure of the air delivered through the nozzle is not large, so that the bulk of the air will pass to the blow-out nozzle F after the controlling valve is open. At the sae time air under pressure will pass gradually through the restricted passage L into the air retaining chamber G1. As soon as pressure air is turned into the system it begins to build up pressure inthe chamber G1 and this pressure accumulates until the total pressure on the side of the partition exposed to the air retaining chamber exceeds that on the side of the partition exposed to the pressure in the air transmission chamber, whereupon the partition and its attached valve will move in a reverse direction to that in which they were originally moved, so as to seat the valve M on the port J and shut olf the `delivery of air to the blow-out nozzle F. Obviously, when the supply of pressure air is cut off the diaphragm and valve will remain in the position in which the valve is seated and the pressure air in the air retaining chamber G1 will escape through the restricted assage L, so that very soon the pressure on oth sides of the diaphragm will be only that of the atmos phere and thus the apparatus will be in position to operate` again on the admission of pressure air to the transmission chamber.

The provisionof the restricted passage e3 leadingto the distributing nozzle E as located in the wall of the air transmission chamv ber G2, is of obvious convenience 'and utility jin a structure such' as 1s shown in `th`e drawing, in which the4 valve casing G is formed integral with the main body casting of the trap.

n, the other end of which is held in a seat o1 I formed inthe cap or cover o, which screws into the threaded end of the casing G. In

place ofthe restricted passage L, Fig. 1, "we,

provide inlthe construction of Fig. 2, 'a restricted passage Z opening, as shown, through the threaded portion of tlief end of the cas# ing G, 'as-shown at Z1 andy :an opening Z2 is formed-through'the wallof'the cap o which lregisters withthe opening Z1 when the -cap is n .l

screwed into place so that air can pass freely into thechamber G1-of the casing. 'It will be obvious that the I'modified construction of Fig. 2 will function in substantially the same Way as does the construction of Fig. 1, although it involves a certain amount of frictional resistance to the movement of the piston, which is avoided in the construction employing a diaphragm, asillustrated in Fig. 1.

In all sander systems in which provision is made for the cleaning out of the delivery pipe by means of an energetic blast of air, it is very important that the delivery of high pressure air to the blow-out nozzle should take place only during a very short period of time,

as otherwise the pressure of air in the air reservoir may fall to an unpermissible amount. At the same time it is obviously desirable that When air isadmitted to the blowout nozzle it should be at high pressure so as to secure the maximum velocity and volume of the jet of air directed into the delivery pipe. It is, therefore, desirable that the valve controllingthe delivery of air to the blow-out nozzle should remain closed until the pressure in the air conduit leading to the trap has time to build up; that the valve should then promptly open and that it should remain open only for a short period and then close with precision and certainty of operation, and it is also important that in case any breakage or disarrangement should occur in the mechanism controlling the movement of the valve that the valve should remain closed. All these considerations have been had in view by us in designing our improved mechanism.

It will be obvious that the time during which the valve M will remainopen will depend to a large extent upon the effective cross sectional area of the restricted passageI leading to the air retaining chamber" and upon the area of the airretaining chamber and that by varying the cubic capacity of the air retaining chamber the period during which the valve will remain open can be fixed at will, that is, the larger this chamber is the longer will be the period during which the y valve will remain open. l Having now described our invention, what we claim as new and desire to secure by Letters Patent, is:

1. An air distributing valve for a pneumatic sander system comprising in combination a casing divided into an air transmitting and an air retaining chamber by a movable partition, a ort connectable with the air supply condult of the system leading into the air transmission chamber, an outlet port from said air transmission chamber connected to the clean-out nozzle of a sand trap,`.a valve for opening and closing said outlet port operatively connected to the movable partition, resilient means tending to shift the partition to the position in which it Will shift. the valve to close the outlet port and a restricted air passage'leading from the air retaining chamber of the casing and vconnectable to the air supply conduit so that when pressure air is directed into the air supply conduit it will Vflow freely into the air transmission chamber of the casing and act-V ing on the movable partitionv shift it to a position in which it will shift the valve to open the outlet port While at the same time f the pressure air will fiow through the restricted passage to the air retaining chamber and gradually build up pressure in said chamf ber to a point where in coaction with the reconsists of a exible diaphragm. v

4. Air controlled mechanism as called for v in c laim 1, in which the casing is formed as an integral part ofthe casting of the sand trap. `v.

5 An air distributing valvey as called for in claim 1, 1n which the casing is formed integral with the casting of the sand trap and in Which the air transmitting chamber is con- C nected with the clean-out nozzle of the trap by a passage formed in the casting and also connected with the nozzle directed into the sand receptacle of the trap by a separate passage formed in the casting.

RALPH A. LIGHT. JOSEPH W.- PRICE, Jn. o 

